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Biomedical subjects

B Scott

Publications and source records attributed to B Scott.

At least 73 records · Page 4Linked to original sources
PubMed1995

A two-year follow-up examination of a behavioural treatment approach to hearing tactics.

Twenty elderly hearing impaired patients participated in a two-year follow-up study on the effects of behavioural treatment aimed at increasing coping with hearing impairment. Subjects who had received treatment were compared with untreated controls using the Hearing Coping Assessment (HCA) and the Communication Strategies Subscale of the Communication Profile for the Hearing Impaired (CPHI-CSS). The group treatment package included applied relaxation, video self-modelling, exposure, information, and the teaching of hearing tactics. Results showed some effects in favour of the treatment on the HCA at post-treatment, but no differences at follow-up. The results on the CPHI-CSS using pre-treatment HCA scores as covariate showed significant multivariate effects on the subscales measuring maladaptive behaviours, non-verbal strategies, and on the CPHI-CSS total score. No significant multivariate effect was found for the verbal strategies subscale. As no pre-treatment data were available, results on the CPHI-CSS should be interpreted with caution. Overall, the results from this study give some support for the implementation of behavioural treatment in audiological rehabilitation.

Adaptation, Psychological↗
PubMed1994

Secretion of thermostable DNA polymerase using a novel baculovirus vector.

Baculovirus-mediated expression has become a powerful tool for the high yield production of functionally active recombinant proteins. In order to further enhance the utility of this expression system, we constructed versatile transfer vectors that facilitate the secretion of recombinant proteins from host insect cells by inserting functional secretory leader sequences down-stream of the polyhedrin promoter. In-frame insertion of cDNA sequences results in the synthesis of fusion proteins containing a heterologous signal sequence which directs the recombinant protein to the secretory pathway. Human and insect leader sequences were successfully tested with a number of proteins including the thermostable Pyrococcus furiousus (Pfu) DNA polymerase in an effort to maximize secretion of heterologous proteins from insect cells. The human placental alkaline phosphatase signal sequence (MLGPCMLLLLLLLGLRLQLSLG) proved to be optimal for the secretion of not only this thermostable bacterial enzyme but also for the secretion of other biologically active polypeptides.

Amino Acid Sequence↗
PubMed1994

2,3,7,8-Tetrachlorodibenzo-p-dioxin reduces the number, size, and organelle content of Leydig cells in adult rat testes.

Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) alters testicular steroidogenesis and reduces total Leydig cell volume in the testis. However, its effect on Leydig cell number, size, and organelle content had not been determined in adult rats. Adult male rats received a single intraperitoneal injection of TCDD at a dose of 0, 12.5, 25.0, or 50.0 micrograms/kg body weight. Testicular tissues were obtained from rats 4 weeks after treatment. Testes were vascularly perfused with glutaraldehyde, embedded in Epon 812, sectioned at 0.5 micron, stained with toluidine blue, and evaluated by stereology for number and size of Leydig cells. Specimens from control and high dose groups were prepared for electron microscopy to quantify Leydig cell organelle content. TCDD treatment reduced (P < 0.01) body weight in a dose-dependent fashion. Testicular weight was not significantly reduced by TCDD treatment. The volume of Leydig cell cytoplasm per testis was reduced (P < 0.01) four weeks after treatment. Reduction in total Leydig cell volume resulted from a reduced (P < 0.05) number of Leydig cells and a reduced (P < 0.01) size of individual Leydig cells. However, the volume density (percentage) of Leydig cells occupied by specific organelles was not influenced by TCDD treatment. As a result of reduced total Leydig cell volume with no change in volume density of organelles in Leydig cells, the volumes per testis of smooth endoplasmic reticulum and mitochondria were reduced (P < 0.01) by TCDD treatment. In conclusion, the TCDD-induced reduction in Leydig cell volume per testis is explained by reduced number and size of individual Leydig cells and resulted in a significant reduction in total volume of both Leydig cell smooth endoplasmic reticulum and mitochondria per testis. Reduction in content of organelles that are responsible for various key steps in steroidogenesis, could explain TCDD-reduced production of testosterone in rats.

Animals↗
PubMed1994

Early identification and isolation of inpatients at high risk for tuberculosis.

BACKGROUND: Although it has been recommended that all patients suspected of having tuberculosis be placed in isolation, the feasibility of this recommendation has not been investigated. METHODS: Forty-three patients with pulmonary tuberculosis were compared with 43 control subjects. The control subjects had submitted expectorated sputum, and were culture negative. Variables included chest roentgenogram results, and risk factors used by the Centers for Disease Control and Prevention (Atlanta, Ga) to identify patients at increased risk for tuberculosis. RESULTS: Potential control subjects outnumbered patients by 92:1. Although a positive tuberculin skin test, foreign birth, and weight loss were more common in the patients, 86% of the control subjects had at least one risk factor for tuberculosis. Chest roentgenograms consistent with tuberculosis (cavities or apical or nodular infiltrates) were found in 86% of the patients, but in only 16% of the control subjects (odds ratio, 31.7; 95% confidence interval, 8.6 to 127.7). The positive and negative predictive values of a consistent chest roentgenogram were 6% and 99.8%, respectively. The sensitivity of testing a single sputum specimen was 81%, yet almost half of the control subjects had only one specimen submitted. Of the inpatient cases, 58% were not identified on admission with a median delay of 13 days before isolation. CONCLUSIONS: Isolating all the patients at the time sputum is submitted for testing is not practical and would have resulted in a 92-fold overuse of isolation rooms. The chest roentgenogram was of great value in identifying patients who did not require isolation and was the best available means of identifying inpatients at high risk for active pulmonary tuberculosis.

Adult↗
PubMed1994

On the various manifestations of spontaneous autoimmune diabetes in rodent models.

Autoimmune (type 1) diabetes mellitus in mouse, rat, and humans shares several features, including T lymphocyte infiltration into pancreatic islets and a dependence on permissive class II major histocompatibility complex (MHC) alleles. We report here on an experimental model involving mice that express influenza hemagglutinin (HA) under the control of the insulin promoter and, at the same time, a transgenic class II MHC-restricted T cell receptor (TcR) specific for an HA peptide. These mice spontaneously develop islet infiltrates resembling those found in NOD mice and most animals become diabetic within 8 weeks of age. Because of the availability of a clonotypic TcR antibody, we can be confident that the Ins-HA transgene does not induce any measurable alterations in the vast majority of T cells with the transgenic TcR in primary and secondary lymphoid organs. Continuous export of large numbers of HA-specific lymphocytes from the thymus was not required for the manifestation of the disease since mice thymectomized at 3 days after birth still developed the disease albeit with smaller infiltrates.

Animals↗
PubMed1994

Integrative transformation of the mycotoxin-producing fungus, Penicillium paxilli.

A high frequency transformation system has been developed for Penicillium paxilli using pAN7-1. Up to 44% of the primary transformants were heterokaryons. Loss of hygromycin resistance was observed in primary transformants that were sub-cultured on non-selective media, but single spores of these primary transformants were mitotically stable on both selective and non-selective media. A molecular analysis of the transformants generated showed that 78% had single-site integrations, with half of these containing a single copy of pAN7-1. CHEF-gel electrophoresis showed that P. paxilli has at least six chromosomes with a total genome size of about 23.4 Mb.

Chromosomes, Fungal↗
PubMed1994

A role for non-MHC genetic polymorphism in susceptibility to spontaneous autoimmunity.

Peripheral immunological tolerance is traditionally explained by mechanisms for deletion or inactivation of autoreactive T cell clones. Using an autoimmune disease model combining transgenic mice expressing a well-defined antigen, influenza hemagglutinin (HA), on islet beta cells (Ins-HA), and a T cell receptor transgene (TCR-HNT) specific for a class II-restricted HA peptide, we demonstrate that the conventional assumptions do not apply to this in vivo situation. Double transgenic mice displayed either resistance or susceptibility to spontaneous autoimmune disease, depending on genetic contributions from either of two common inbred mouse strains, BALB/c or B10.D2. Functional studies on autoreactive CD4+ T cells from resistant mice showed that, contrary to expectations, neither clonal anergy, clonal deletion, nor receptor desensitization was induced; rather, there was a non-MHC-encoded predisposition toward differentiation to a nonpathogenic effector (Th2 versus Th1) phenotype. T cells from resistant double transgenic mice showed evidence for prior activation by antigen, suggesting that disease may be actively suppressed by autoreactive Th2 cells. These findings shed light on functional aspects of genetically determined susceptibility to autoimmunity, and should lead to new therapeutic approaches aimed at controlling the differentiation of autoreactive CD4+ effector T cells in vivo.

Animals↗
PubMed1994

Sperm motility, morphology, hyperactivation, and ionophore-induced acrosome reactions after overnight incubation with mycoplasmas.

OBJECTIVE: To evaluate the effect on the function on human sperm of overnight incubation with mycoplasma species. DESIGN: Prospective controlled in vitro study. SETTING: Community-based sperm bank and andrology laboratory. INTERVENTIONS: Percoll-separated sperm were incubated overnight with a low densities of Myco-plasma hominis and Ureaplasma urealyticum serotypes. MAIN OUTCOME MEASURES: Motility, midpiece and tail morphology, hyperactivation after overnight capacitation, and acrosome status after incubation with calcium ionophore. RESULTS: Overnight incubation with mycoplasma species resulted in small but highly statistically significant differences in motility, morphology, hyperactivation after overnight capacitation, and proportion acrosome reacted after incubation with calcium ionophore compared with controls. CONCLUSIONS: Incubation with mycoplasma species impairs sperm physiology. Identification and treatment of mycoplasma may augment a physiology-based infertility evaluation.

Acrosome↗
PubMed1994

Should an athlete eat straight after training?--A study of intestinal transit time and its relationship to prior exercise.

The mouth-to-caecum transit time of food was measured using the rise in breath hydrogen after a standard breakfast of baked beans on two occasions in seven healthy volunteers. The first occasion was after resting and the second after moderate exercise on a bicycle ergometer. There was no significant difference between the transit times with or without prior exercise. It is concluded that moderate exercise taken before food does not interfere with transit time and therefore should not in that way interfere with nutrition.

Adolescent↗
PubMed1994

Management of the thyroid isthmus in tracheostomy: a prospective and retrospective study.

The thyroid isthmus is often encountered while a tracheostomy is being performed. This study details retrospective and prospective comparison of electrocautery division of the isthmus with older techniques. In this study, electrocautery division of the thyroid isthmus during tracheostomy is faster and as safe as other techniques with respect to blood loss, perioperative complications, and airway outcome.

Blood Loss, Surgical↗
PubMed1994

Behavioral counselling for subjects with acquired hearing loss. A new approach to hearing tactics.

Effects of behavioral counselling of subjects with an acquired hearing loss were evaluated in an experimental design. The study included a group of 20 hearing-impaired subjects who were assessed and randomly allocated to a treatment or control group. Behavioural counselling, individualized according to the results of functional analysis, was then given to 10 subjects and included the teaching of 'hearing tactics'. The groups were measured three times, pre-counselling and post-counselling and at a 15-month follow-up, after which treatment results were analysed. Significant (time x treatment) interactions were followed by post-hoc testing revealing that the treated group had improved in several areas of functioning while controls had not. These results were in agreement with interview data. The findings indicate that a behavioural counselling approach to hearing tactics is beneficial in the understanding and rehabilitation of hearing loss, especially over time.

Adaptation, Psychological↗
PubMed1994

An experimental evaluation of the effects of transcutaneous nerve stimulation (TNS) and applied relaxation (AR) on hearing ability, tinnitus and dizziness in patients with Menière's disease.

In 20 patients diagnosed with Menière's disease, transcutaneous nerve stimulation (TNS) and applied relaxation (AR) were used as a treatment aimed at reducing tinnitus and dizziness and increasing hearing ability. The main aim of the study was to examine whether TNS could be regarded as a more beneficial treatment regimen than AR. An experimental between-group cross-over design was used. The results from the experimental phase (group comparisons) showed a significantly increased ability to hear for the TNS group when measured on visual analogue scales. During the same period, the AR-group showed a significant hearing improvement for the ear not primarily affected by Menière's disease as measured with pure tone audiometry. The vestibular tests did not reveal any significant changes either after TNS or AR intervention. Tinnitus matching showed changes of pitch and loudness before and after both TNS and AR intervention. However, no statistically significant changes between treatment regimes were found on these measures. The results from this study did not show TNS to be superior to AR in reducing tinnitus, dizziness or increasing hearing ability.

Adult↗
PubMed1993

Antigen-presenting cells in adoptively transferred and spontaneous autoimmune diabetes.

Histological techniques were used to identify antigen-presenting cells (APC) in adoptively transferred diabetes in NOD mice and Ins-HA transgenic mice, and in spontaneously diabetic NOD mice. In adoptively transferred disease, CD4+ T cells and F4/80+ macrophages dominated early infiltrates. By contrast, in spontaneously developing diabetes in NOD mice, lymphocytic infiltrates appeared to be well organized around a network of VCAM-1+ NLDC-145+ ICAM-1+ dendritic cells. Thus, the primary APC spontaneous autoimmune disease appears to be the strongly stimulatory dendritic cell rather than the normally resident macrophage. Next, we used chimeric animals to demonstrate that insulitis and diabetes could occur even when responding T cells were unable to recognize islet-specific antigen directly on beta cells. Altogether, the results demonstrate that immune-mediated damage does not require direct contact between CD4+ T cells and beta cells. Moreover, despite the induction of ICAM-1, VCAM-1, and class II on vascular endothelium near islet infiltrates, these experiments show that recruitment of lymphocytes occurs even when antigen presentation is not possible on vascular endothelium.

Amino Acid Sequence↗
PubMed1993

Fungal symbionts of grasses: evolutionary insights and agricultural potential.

Some filamentous fungal endophytes confer on their grass hosts important biological properties including resistance to grazing herbivores and resistance to nematodes and some fungal pathogens, as well as drought tolerance and greater field persistence. The production of alkaloids toxic to grazing animals is an undesirable aspect of the association in agronomic situations. Consequently, genetic strategies are being pursued to manipulate fungal endophytes and their hosts for agricultural benefit.

Agriculture↗